How to get the Value by a Key in JavaScript Map?

JavaScript Map is a powerful data structure that provides a convenient way to store key-value pairs and retrieve values based on keys. This can be especially useful when we need to associate specific data with unique identifiers or keys.

Different Approaches to Get the Value by a Key in JavaScript Map

Using the get() method

The get method of the Map object is used to retrieve the value associated with a specified key.

Syntax:

map.get(key)

Example: This example uses the, get method to retrieve the value.

let map = new Map();
map.set('name', 'GeeksforGeeks');
map.set('CEO', 'Sandeep Jain');
console.log(map.get('name'));
console.log(map.get('CEO'));

GeeksforGeeks
Sandeep Jain

Using forEach method

In this approach, iterate we will use forEach method to iterates over each key-value pair in the Map. It takes a callback function as an argument, which is called with each key and value in the Map. In this case, the callback function checks if the key matches the desired key and assigns the corresponding value to the value variable.

Syntax:

Object.forEach(function(currentValue, index) {  
});

Example: Below example use forEach method to retrieve the value of provided key.

let map = new Map();
map.set('name', 'GeeksforGeeks');
map.set('CEO', 'Sandeep Jain');
map.set("est", 2009)

let value;
map.forEach((val, key) => {
    if (key === 'name') {
        value = val;
    }
});
console.log(value);

GeeksforGeeks

Using Array.from() and find() method

In this approach, we are using Array.from() to convert the Map entries into an array of key-value pairs. Then, we apply the find() method to search for the entry where the key matches the specified key.

Syntax

Array.from(object, mapFunction, thisValue)
array.find(function(currentValue, index, arr), thisValue)

const map = new Map();
map.set('name', 'GeeksforGeeks');
map.set('CEO', 'Sandeep Jain');
const key = 'name';
const value = Array.from(map).find(([k, v]) => k === key)?.[1];
console.log(value);

GeeksforGeeks

Using Spread Operator and find() Method

Another approach to retrieve a value by key in a JavaScript Map is by using the spread operator (...) to convert the Map entries into an array of key-value pairs and then applying the find() method to search for the entry where the key matches the specified key. This method provides a clear and concise way to work with Map entries.

Example: The following example demonstrates how to use the spread operator and find() method to retrieve the value associated with a specific key in a Map.

const map = new Map([
  ['a', 1],
  ['b', 2],
  ['c', 3]
]);

function getValueByKey(map, key) {
  const entry = [...map].find(([k, v]) => k === key);
  return entry ? entry[1] : undefined;
}

const keyToFind = 'b';
const value = getValueByKey(map, keyToFind);
console.log(`The value for key '${keyToFind}' is ${value}`); // Output: The value for key 'b' is 2

The value for key 'b' is 2

yuvrajghule281

Follow

Improve

Article Tags :

• JavaScript
• Web Technologies
• JavaScript-Questions